Symmetrical vs Flat Bottom Wing - RC Groups
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Oct 24, 2010, 08:05 AM
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Chophop's Avatar

Symmetrical vs Flat Bottom Wing

I seem to see more flat wing planes than symmetrical. I have flown both and when landing or maneuvering, prefer symmetrical. When Sport flying light aerobatics at low or medium speeds, flat bottom seems best for lower battery drain at low speeds.

It also seems a symmetrical has a higher top speed but not so good glide. So, maybe a nearly symmetrical is a good compromise for all around flying.
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Oct 24, 2010, 09:10 AM
ChrisS's Avatar
"I seem to see more flat wing planes than symmetrical."

Wow, kind of hard to believe. A quick walk through any hobby shop these days reveils a ton of 3D and sport planes, the vast majority of which will be symmetrical. Pretty much the only planes using flat bottomed or semi-symmetrical would be gliders, trainers and some scale stuff. Most of which are not used for much more than basic flying and rudimentary aerobatics.

You have it right though, flat bottomed or SS are true lifting bodies and do not need incidence to fly (assuming they are moving forward fast enough). As such they will generally fly slower and more efficiently for a given unit of thrust.

However, as you may have seen, big, floaty, lightly loaded, symmetrical airfoiled planes can be slowed down to a hover and flown on prop thrust alone (o.k. you could do that with a flat bottomed wing too, but most don't)...

Flat bottomed and SS do not penetrate as well into wind, tend to jump around more in turbulence and do not fly the same inverted as they do right side up.

For all out speed, you would want a lifting type of wing (one that does not need incidence to fly as this is very draggy). Then it's a matter of thinning it enough to reduce the profile drag (so that it's easier to push through the air) but not so much that you loose lift.

To glide a symmetrical wing, you of course can add camber with flaps or flapperons. Lightly loaded, this technique can work very well for gliding. However a true lifting airfoil is always best for this. But not as much fun when you want to blow holes in the sky.

You buy your ticket and take your ride.


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